The disclosed technology relates to lubricant compositions containing a soluble titanium-containing material and a soluble molybdenum-containing material, having beneficial effects on properties such as deposit control, oxidation, and filterability in, for instance, lubricants for engines. Other materials used in combination with titanium are also useful in lubricants.
Current and proposed specifications for crankcase lubricants, such as GF-4 for passenger car motor oils, and PC-10 for heavy duty diesel engines specify increasingly stringent standards to meet government specifications. Of particular concern are sulfur and phosphorus limits. It is widely believed that lowering these limits may have a serious impact on engine performance, engine wear, and oxidation of engine oils. This is because historically a major contributor to phosphorus content in engine oils has been zinc dialkyldithiophosphate (ZDP), and ZDP has long been used to impart antiwear and antioxidancy performance to engine oils. Thus, as reduced amounts of ZDP are anticipated in engine oils, there is a need for alternatives to impart protection against deterioration in one or more of the properties of engine performance, engine wear, and oxidation of engine oils. Such improved protection is desirable whether or not ZDP and related materials are included in the lubricant. Desirable lubricants may be low in one or more of phosphorus, sulfur, and ash, that is, sulfated ash according to ASTM D-874 (a measure of the metal content of the sample).
US Published Application 2006-0217271, Brown et al., Sep. 28, 2006, discloses a lubricating composition comprising an oil of lubricating viscosity and 1 to 1000 parts per million by weight of titanium in the form of an oil-soluble titanium containing material. Additional additives may be present. A possible component may be an antioxidant, among which are disclosed phenolic antioxidants, aromatic amines, sulfurized olefins, and molybdenum compounds.
U.S. Pat. No. 7,615,520, Esche et al., Nov. 10, 2009, discloses a lubricated surface that includes a lubricant composition containing a base oil of lubricating viscosity and an amount of at least one hydrocarbon soluble metal compound effective to provide a reduction in oxidation of the lubricant composition. The metal of the metal compound is selected from the group consisting of titanium zirconium, and manganese. A sulfur- and phosphorus-free organomolybdenum compound may be used as a friction modifier. In certain examples, titanium neodecanoate is top-treated onto a base oil composition that contains, among other materials, a molybdenum containing friction modifier.
U.S. Pat. No. 7,615,519, Esche et al., Nov. 10, 2009, discloses a lubricated surface containing a base oil of lubricating viscosity and an amount of a hydrocarbon soluble titanium compound effective to provide a reduction in surface wear.
U.S. Pat. No. 6,624,187, Schwind et al., Nov. 4, 2003, discloses lubricating compositions, concentrates, and greases containing the combination of an organic polysulfide and an overbased composition or a phosphorus or boron compound. Metals which can be used in the basic metal compound include (among others) titanium.
International PCT Publication WO 2006/044411, Apr. 27, 2006, discloses a low-sulfur, low-phosphorus, low-ash lubricant composition containing a tartrate ester or amide having 1 to 150 carbon atoms per ester or amide group. The lubricant composition is suitable for lubricating an internal combustion engine.
It has now been discovered that the presence of titanium, supplied, for instance, in the form of certain titanium compounds, provides a beneficial effect on one or more of the above properties. In particular, such materials as titanium isopropoxide or 2-ethylhexoxide impart a beneficial effect in one or more of the Komatsu Hot Tube Deposits screen test (KHT), the KES Filterability test, the Dispersant Panel Coker test (a test used to evaluate the deposit-forming tendency of an engine oil) and the Cat 1M-PC test. Combinations of such titanium compounds with other additives, to be described in detail below, can provide additional benefits as hereinafter described.